This invention relates to an apparatus for casting ceramic holloware More specifically, the present invention relates to an automated rotatable carriage for retaining a plurality of ceramic holloware molds between upper and lower members and including means for equalizing clamping pressure over the surface of the molds to secure the molds within the carriage while the molds are rotated through a variety of positions. An automatic filling system is provided to automatically and sequentially fill each of a plurality of molds with ceramic slip material.
In the molding of ceramic holloware, those skilled in the art have generally utilized a carriage having a pair of frame members to clamp a plurality of plaster molds therebetween. The clamped molds are generally rotated to successive positions about a horizontal axis during different stages of the casting process. Such an apparatus for casting ceramic holloware may further include an inflatable member or balloon positioned along the inner face of one of the frame members to secure the molds in place within the carriage during rotation. When provided, the inflatable member or balloon equalizes clamping pressure over the surface of each mold by providing maximum surface area contact between the molds and the frame member associated with the balloon.
Where provided in the prior art, the inflatable member has generally been inflated only after the upper frame member has been locked in position to clamp the molds within the carriage After casting, the balloon is deflated and the upper frame member is again opened. This constant inflation and deflation of the inflatable member is an unnecessary step in the casting process Although the use of an inflatable member is generally useful for securing a plurality of molds in a clamped position, the prior art has failed to provide a casting device wherein the carriage is completely automated and wherein the upper frame member is equipped with a constant pressure air-filled bag.
The present invention provides an automated apparatus for casting wherein a plurality of molds are placed on a table or a lower member of a carriage. The molds are clamped within the carriage by an automated upper member which is lowered into a clamping position so that the upper and lower members are substantially parallel to each other with the molds secured therebetween. A constant pressure air bag or balloon is affixed along the underside of the upper member and extends longitudinally therealong. When the upper member is in the clamping position, the air bag is sandwiched between the molds and the underside of the upper member. In this manner, the molds are secured in their relative positions within the carriage by the balloon which serves to equalize the clamping pressure over the surfaces of all of the molds. Sensing means are provided so that the upper frame member will automatically adjust to a predetermined clamp pressure.
After the molds have been secured the carriage is automatically rotated to position the molds for sequential filling by an automatic filler which fills each mold cavity with ceramic slip material. An automatic filler suitable for use herein is described in U.S. Pat. No. 4,102,267, the disclosure of which is incorporated by reference herein.
The filled molds are allowed to set for a predetermined period of time in order for the slip to form a soft casting. Following the predetermined set time, the carriage automatically rotates further to pour the excess slip from the molds while the molds are held in a inverted position for a predetermined "drip time". Following the drainage of the molds, the carriage is returned to the initial horizontal position for unloading. Once the carriage has been returned to its initial position, the clamp automatically opens so that the castings may then be removed from the molds.
Automation is accomplished by a pair of motors and related controls A clamp motor drives the upper clamp member between an opened and a closed position A load detector, associated with the clamp motor, shuts the motor off upon sensing that a predetermined clamp pressure has been attained. A carriage positioning motor and related gearing rotationally drives the carriage to position the molds in the orientations necessary for casting A programmable carriage control operates the carriage positioning motor once the molds have been securely clamped within the carriage to position the carriage and the molds in the "fill" position wherein a fill control operates the filler to sequentially fill each of the molds secured within the assembly. After completion of the filling sequence, the fill control returns the auto filler to its initial position and the ceramic slip within the molds is allowed to set for a preset time after which the carriage control again rotates the carriage and molds to spill out excess slip and the molds are maintained by the carriage control in an inverted position for a preset "drip" time. The carriage control then re-positions the carriage and molds to the load/unload position to then enable the clamp motor to open the clamp so that the molds can be opened and the soft clay castings removed from within.
Accordingly, it is an object of the present invention to provide an automated apparatus for casting ceramic holloware having a rotatable table assembly or carriage mounted on a frame, the table assembly including upper and lower clamp members for retaining a plurality of molds therebetween with automated control means for positioning the upper clamp member between an opened position and a closed position, and automated rotation means for rotating the carriage when the upper clamp member is in the closed position.
It is another object of the present invention to provide the above-described automated apparatus for casting ceramic holloware and further including an air bag or cushion positioned along the upper clamp member to contact the plurality of molds when the upper clamp member is in the closed position.
It is still another object of the present invention to provide the above-described automated apparatus for casting ceramic holloware and further including an automated filler for filling each of the plurality of molds.